Constitutive Modeling of a Schistose Rock in the Himalaya

Strain‐controlled triaxial tests have been conducted using servo‐controlled loading system on three schistose rocks from a hydropower project in the Himalaya. A constitutive model based on the disturbed state concept is used to model the behavior of the rocks. Predictions are made using a single point method and finite element method. The constitutive model is found to provide satisfactory predictions. The DSC model is used to predict observed behavior of a powerhouse cavern; the relevant paper, “Analysis of a Powerhouse Cavern in the Himalaya,” appears in this issue.     

Bioadsorber efficiency,design, and performance forecasting for alachlor removal

This study discusses a mathematical modeling and design protocol for bioactive granular activated carbon (GAC) adsorbers employed for purification of drinking water contaminated by chlorinated pesticides, exemplified by alachlor. A thin biofilm model is discussed that incorporates the following phenomenological aspects: film transfer from the bulk fluid to the adsorbent particles, diffusion through the biofilm immobilized on adsorbent surface, adsorption of the contaminant into the adsorbent particle. The modeling approach involved independent laboratory-scale experiments to determine the model input parameters. These experiments included adsorption isotherm studies, adsorption rate studies, and biokinetic studies. Bioactive expanded-bed adsorber experiments were conducted to obtain realistic experimental data for determining the ability of the model for predicting adsorber dynamics under different operating conditions. The model equations were solved using a computationally efficient hybrid numerical technique combining orthogonal collocation and finite difference methods. The model provided accurate predictions of adsorber dynamics for bioactive and non-bioactive scenarios. Sensitivity analyses demonstrated the significance of various model parameters, and focussed on enhancement in certain key parameters to improve the overall process efficiency. Scale-up simulation studies for bioactive and non-bioactive adsorbers provided comparisons between their performances, and illustrated the advantages of bioregeneration for enhancing their effective service life spans. Isolation of microbial species revealed that fungal strains were more efficient than bacterial strains in metabolizing alachlor. Microbial degradation pathways for alachlor were proposed and confirmed by the detection of biotransformation metabolites and byproducts using gas chromatography/mass spectrometry.     

Synthesis and Characterization of Metal Nanoparticle Embedded Conducting Polymer–Polyoxometalate Composites

Phosphomolybdate has been employed simultaneously as the oxidizing agent for the monomer polymerization and the reduced polyoxometalate is used as reducing agent for the reduction of metal ions. The composites thus obtained have been characterized and may have many potential applications.     

Tension and fatigue behavior of silver-cored composite multi-strand cables used as implantable cables and electrodes

The mechanical behavior of a variety of cable architectures comprised of silver-cored wires was evaluated in uniaxial tension, and in cyclic strain-controlled fatigue with the use of a flex tester operated to provide fully reversed bending fatigue. The magnitude of cyclic strains imparted to each cable tested was controlled via the use of different diameter mandrels. Smaller diameter mandrels produced higher values of cyclic strain and lower fatigue life. Multiple samples were tested and analyzed via scanning electron microscopy. The fatigue results were analyzed via a Coffin–Manson–Basquin approach and compared to fatigue data obtained on 316LVM cables where testing was conducted in an identical manner. The effects of changes in wire diameter, cable architecture, and wire composition (i.e. silver-cored vs. 316LVM) are discussed.     

Microwave-assisted rapid synthesis of anisotropic Ag nanoparticles by solid state transformation

Anisotropic silver nanoparticles (NPs) have been synthesized rapidly using microwave irradiation by the decomposition of silver oxalate in a glycol medium using polyvinyl pyrolidone (PVP) as the capping agent. The obtained Ag nanoparticles have been characterized by UV-visible spectroscopy, powder x-ray diffraction (XRD), transmission electron microscopy (TEM) and high-resolution TEM (HRTEM) studies. Anisotropic Ag nanoparticles of average size around 30?nm have been observed in the case of microwave irradiation for 75?s whereas spherical particles of a size around 5-6?nm are formed for 60?s of irradiation. The texture coefficient and particle size calculated from XRD patterns of anisotropic nanoparticles reveal the preferential orientation of (111) facets in the Ag sample. Ethylene glycol is found to be a more suitable medium than diethylene glycol. A plausible mechanism has been proposed for the formation of anisotropic Ag nanoparticles from silver oxalate.     

Development of High Performance Steel Products in Sail Through R&D Initiatives

Steel Authority of India Limited (SAIL), through its Corporate R&D i.e. RDCIS, has been working incessantly for the development of new steel products with superior quality attributes to meet the requirements of Indian market. The product development activities have always been supported by in-house/collaborative research work which has led to deeper understanding on the process know-how, resulting in launching of cost-effective products in Indian market. Some of the products developed by SAIL in the flat product category include high strength thin gauge HR coil for automobile sectors, SAILMA 550 HI/SAILMA 600 grade plates for penstocks and earthmovers, SAIL HITEN 690 AR plates for automated teller machines chest, high strength plates with guaranteed through thickness ductility for railways and Defence sectors, boiler quality plates (ASTM 387 Gr. 12) for power sector, API X 70 grade HR coils and plates for Linepipe application. In the long products category, EQR TMT rebar, Roof/Rock Bolt (Fe—600) TMT rebars for mines and tunnels, corrosion resistant TMT rebars for construction sector, Al-killed low carbon CC blooms for cold reducers, Al-killed medium carbon CC blooms for forging have been developed recently through R&D initiatives in SAIL. This paper describes some of the products which were recently developed in SAIL.     

Zur Struktur geschmolzener CaO-SiO2-Al2O3-Schlacken

Methode zur Berechnung mittlerer molarer Massen von ringförmigen Anionenkomplexen in CaO-SiO₂-Al₂O₃-Schlacken. Annahme von dreifacher oder vierfacher Koordination für Aluminium. Korrelierung von Schrifttumswerten der Viskosität mit berechneten Anionenmassen.     

Influence of magnetorheological elastomer on tool vibration and cutting performance during boring of hardened AISI4340 steel

During boring process, tool vibration is a major concern due to its overhanging length, which results in high cutting force, poor surface finish, and increase in tool wear. To suppress tool vibration and improve cutting performance, a novel technique in rheological fluid was designed and developed. In this work, a magnetorheological elastomer (MRE) was developed, and parameters, such as piston location, current intensity, and coil winding direction, were considered. Cutting experiments were conducted to obtain a set of parameters that can efficiently control vibration during boring of hardened AISI 4340 steel. Taguchi method was used to optimize the cutting condition, and findings show that the cutting tool embedded with the MRE reduced tool vibration and effectively increased cutting performance.